Thanks all for the advice! So it turned out to be two challenges for me.
One was indeed turning on the ampflifier in the antenna. Neighbors at the Trap Pond rally pointed out that the switch is actually next to a 12V
power jack under the dinette table, next to the cable bypass box. After extending the antenna, I turned that on, green light indicator on.
Second challenge was the digital TV converter box that the previous owner had installed for reception. I made sure all cables were connected, then tried to bring up the menu on the TV set to channel 3. Turns out the remote had corroded battery terminals, which I scraped clean and inserted a new set of batteries. That allowed me to bring up the menu, did an auto-scan of channels, and VOILA! It saved a few dozen channels which I'm easily able to surf.
So thanks all again for the pointers!